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OpenMM(tm) Example programs and prototype C and Fortran wrappers
June, 2009
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These simple "hello world" examples were developed by
Christopher Bruns and Michael Sherman for the OpenMM
workshop on June 24, 2009 at Stanford.

There are also two sets of prototype wrappers to enable C
and Fortran 95 to call the OpenMM API. However, even if
your calling code is in C or Fortran, please consider instead
writing your OpenMM-calling routines in C++, using 'extern "C"'
so that your main program can call them. If that isn't feasible
for you, try out our prototype wrappers and let us know what
troubles or better ideas you have.

HelloArgon (C++, C, Fortran 95)
-------------------------------

This is the simplest example we could come up with that
does anything interesting. It is three argon atoms interacting
in a vacuum via van der Waals forces. It is primarily so you can
check that you are able to compile, link, and run correctly with
OpenMM. You will also get a many-frame pdb file generated
which you can view as an animation in VMD or most other
molecular viewers.

HelloSodiumChloride (C++, C, Fortran 95)
----------------------------------------

This example shows how we recommend using OpenMM so that you
can call it from an existing Molecular Dynamics code with
minimal disruption. The example contains Coulomb and van der 
Waals interactions and implicit solvation in a constant temperature simulation.

HelloEthane (C++ only)
----------------------

This example shows how to convey bond information to 
OpenMM. It is organized similarly to HelloSodiumChloride.

HelloWaterBox (C++ only)
------------------------

This example shows use of explicit solvent in a periodic box.
It is organized like the previous two.


C Wrapper
---------

This consists of two files:
    OpenMM_CWrapper.h
    OpenMM_CWrapper.cpp

Your C code (and the C examples above) include the header file
and link with OpenMM_CWrapper.o along with the OpenMM library.
Consult the code or the example programs to figure out how
to use the wrappers; they are for the most part a very 
straightforward rehashing of the well-documented OpenMM C++
API.

Fortran Wrapper
---------------

The file that defines the OpenMM module is:
     OpenMM_Module.f90

This consists of a Fortran '95 Module "OpenMM" so that your
Fortran program units have "use OpenMM" statements. You will
need access to the OpenMM*.mod files generated for the modules,
and you must also link with the OpenMM_CWrapper.o as described
above for C. That's because the C Wrapper also provides bindings
that treat arguments in a manner appropriate to Fortran, and 
the Fortran Module describes those rather than attempting to
match the C or C++ signatures.









